* Energy stocks will be in focus as the industry braces for Hurricane Harvey which may become the biggest storm to hit the U.S. mainland in more than a decade. Oil prices were up about 0.6 percent.

* Shares of consumer staples will also be in focus after Amazon laid out plans, including price cuts for range of products, as it completes its purchase of Whole Foods . Shares of rival grocers tumbled Thursday.

* Yellen’s speech on financial stability is scheduled for 10:00 a.m. ET (1400 GMT), while European Central Bank President Mario Draghi is slated to speak at 03:00 p.m. ET.

* Although there are slim chances for policy announcements, investors will scrutinize Yellen’s speech for more clarity on the timing of the Fed’s unwinding of its massive bond holdings and if a third interest rate hike this year is on the cards.

* While inflation remains stuck below the central bank’s 2-percent target, a low unemployment rate and low bond yields could still argue the case for another hike. The chances of a move in December stand at 37.6 percent, according to CME Group’s FedWatch tool.

* The shift in focus to monetary policy comes after weeks of political uncertainty in Washington, concerns over geopolitics and President Donald Trump’s controversial comments that have kept the investors on edge.

* Trump will launch major push on tax reform next week with a speech in Missouri, Gary Cohn, head of White House national economic council, told the Financial Times.

* Shares of Autodesk were up about 5 percent in premarket trading after the software maker reported a smaller-than-expected loss and raised its forecast.